Truss end pad fitting

ABSTRACT

A mechanical fitting for connecting structures may include a base structure and a plate member. The mechanical fitting may also include a support structure for supporting the plate member at a predetermined spacing from the base structure. The support structure may include a truss structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of application Ser. No.13/289,031, filed Nov. 4, 2011.

FIELD

The present disclosure relates to aircraft, aerospace vehicles, othervehicles and other structures, and more particularly to truss end padfittings that connect two structures and transfer axial loads betweenthem with a minimum of bending and shear stresses in the fittings.

BACKGROUND

Structures, such as aircraft, civil structures and other largestructures, may be built from assemblies, which in turn may be builtfrom subassemblies. In such structures transmitting large loads betweenone assembly and an adjacent assembly or subassembly is often necessary.For example, one semi-span of an aircraft wing may be attached to astructure on the fuselage. As the wing bends upward due to upward airloads acting upon the wing, compression stress is caused in the upperwing surface and tension loads are created in the lower wing surface. Atthe root of the wing where the wing attaches to the aircraft fuselage oranother semi-span depending on the wing design, transferring the largecompression or tension loads from one structure to another may benecessary. Transferring tension loads are more challenging thancompression loads for reasons described herein. Structural details ormechanical devices that are often used to transmit these loads aretypically referred to as tension clips or tension fittings. Examples ofdifferent types of such fittings are illustrated in FIGS. 1-4. Thedimensions of the various components of such fittings may vary widely.The different types of fittings may include similar components asdescribed herein. FIG. 1 is a perspective view of an example of a priorart angle clip 100 useable in connecting structures. The angle clip 100may include an end pad 102. The end pad 102 may include an opening 104formed therein for receiving a fastener 106, such as a bolt or othertype fastener. The fastener 106 may include a shank 109 and a head 110.Opening 104 is sized to prevent the head 110 of the fastener 106 frompassing through the opening 104. The end pad 102 may be a plate thatcarries the fastener load to any adjoining walls by shear and bendingforces or loads similar to those illustrated in FIG. 2B. Typically, theend pad 102 is substantially quadrilateral in shape, for examplesubstantially rectangular.

The fastener 106 or bolt may connect the angle clip 100 or other fittingto a mating fitting on an adjacent structure. The angle clip 100 orother fitting may abut a mating fitting on the adjacent structure. Anexample of a fitting abutting a mating fitting that is attached to anadjacent structure is illustrated in FIG. 14.

All tension clips and fittings described herein have certain features incommon related to how they transmit tension loads between twostructures: Tension loads are transmitted to a fitting from onestructure through the fitting's walls attached (or integral) to thatstructure and these loads are transmitted to another structure via atension fastener (or fastners). FIG. 2B illustrates tension forcesacting on the side walls and tension fastener shank 109 of a channeltension clip. Thus, for a pair of mating fittings, highly loaded suchthat the end pads bend and the side walls between the two adjoiningfittings separate from each other, the load path can be described asfollows: tension load travels from a structure into the side walls ofone fitting to the end pad of that fitting, through the tension boltinto the end pad of the adjoining fitting, and then to the side walls ofthe that adjoining fitting, and then to the adjoining structure.

The angle clip 100 may include an adjoining wall or side wall 108 thatmay project substantially perpendicular to the end pad 102 andsubstantially parallel to an axis of the fastener 106 or bolt. A fittingincluding three of the four sides of a quadrilateral end pad 102 havingadjoining side walls is referred to as a channel fitting. An example ofa channel fitting 400 including three adjoining side walls 402, 404 and406 is illustrated in FIG. 4. The side wall 406 of a channel fitting isalso referred to as a back plane. If only two sides that meet in acommon corner are joined to the end pad 102, the fitting is termed anangle fitting. An example of an angle fitting 300 including two adjacentjoining side walls 302 and 304 is illustrated in FIG. 3. If only one ofthe sides of the quadrilateral is joined to a side wall, the fitting istermed an angle clip 100 as illustrated in FIG. 1. If two opposite sidesof the quadrilateral end pad 102 are each joined to a side wall 202 and204, the fitting is termed a channel tension clip. An example of achannel tension clip 200 is illustrated in FIG. 2A with the two oppositeside walls 202 and 204.

On a weight efficiency basis, channel tension fittings are moreefficient than channel fittings, which in turn are more efficient thanangle fittings, which in turn, are more efficient than channel or angleclips. While machining cost does influence the design of channelfittings and channel tension clips, minimizing weight of any structuralcomponents of an aircraft or structure to be used in outer space ishighly desirable. This is because, over the life of the structure, eachunit of weight for each part of the vehicle represents a very largeamount of fuel with an associated cost. Since the weight savings allowsthe total vehicle weight to be reduced, there may also be other benefitsor advantages, such as for example manufacturing and maintenance costs.The design of the fittings described with reference to FIGS. 1-4 resultsin a part with a certain weight, depending on such parameters as theaxial load, the location of the fastener or bolt with respect to theadjoining walls, and the material properties of the fitting.Accordingly, there is a need for fittings and other components which canreduce weight of a part or assembly without sacrificing structuralintegrity or incurring a prohibitive manufacturing or maintenance cost.

Additionally, the axial load, as illustrated by arrow 206 in FIG. 2B,from the fastener 106 or bolt is also transferred into the end pad 102as illustrated in FIG. 2B primarily by the mechanism of the fastenerhead 110 clamping the end pad 102. From there, the load is transmittedto the side walls 202 and 204 by combined shear and bending forces. Inother words, the end pad 102 behaves similar to a beam. Sincetransferring loads from one point to another point by bending is not asefficient as transferring loads by axial force, there is an inherentinefficiency in using plates in bending to transfer the load.

The use of a bolt forces a certain amount of eccentricity into theconnection. Because the bolt has a head which is typically 1.6 times thediameter of the bolt shank, the side walls cannot be any closer than 0.8times the diameter of the bolt from the axis of the bolt. However, thefittings also need to be constructed with generous fillet radii at thejunction of the end pad 102 and side walls 108, 202, 204, 302, 304, 402,404 and 406 to preclude cracking, further increasing the eccentricity.In addition, unless an internal socket head is used, it is necessary fora socket wrench to fit over the head of the bolt. This minimumeccentricity forces the end pad to be a certain minimum size. For beams,increased length results in increased stresses, which result ininefficiency.

Tension bolts in traditional tension fittings and clips are often sizedto have large diameters, in order to increase fitting end pad bendingstrength. Larger bolt heads increase fitting strength by reducingmoments induced in the end pad (specifically by reducing the effectiveend pad “lever arm” length, the span between the edge of the bolt andthe fitting walls). However, this approach to increasing fittingstrength results in a weight penalty. The large heavy bolts usedfrequently end up having greater tension capacity than the fittingitself, which results in structural inefficiency.

The geometry of the fittings and the path of the load through the endpad 102 into the sidewalls require that the locations of high stress dueto bending pass through the corners where the side walls 202 and 204 arejoined to the end pad 102. This area of the structure has a high stressconcentration coefficient for loading as illustrated in FIG. 2B. Thus,even though a generous fillet radius is provided, fittings aresusceptible to fatigue cracking at these locations.

Since fittings are often made out of plate or extrusion, there is alwaysa fillet 210, such as fillet 210 in FIG. 2B for which the direction ofmaximum stress is oriented in the short transverse material direction ofthe plate 212 as illustrated in FIG. 2B. This material direction isusually the weakest and most brittle direction. Since it is unavoidableto load at least one fillet in this direction, it is necessary to selectmetallic alloys that are not as brittle. However, the price for thisadditional ductility is a reduction in ultimate strength. This reductionin allowable stresses results in increased inefficiency of the fitting.

A bolt is comprised of a shank and a head. The shank portion has athreaded portion which accepts the nut that is screwed onto the bolt,and an unthreaded portion. Under axial tension load, the location ofmaximum stress occurs at the net area under the first thread. Thus, thematerial of the bolt in the unthreaded area is not loaded to theultimate capacity of the material because it is limited by the net areaunder the threads. In addition, the threads introduce a stressconcentration due to the notch created by the thread. Thus, a threadedbolt itself has an inherent inefficiency. This inefficiency forces thediameter of the bolt to be larger than it would have been if theseeffects were not present, which in turn, forces the end pad to be widerthan it otherwise would need to be. Thus the inefficiencies in the bolthave a compounding effect on the rest of the fitting. This compoundingeffect works in the reverse direction also. Increased eccentricities inthe joint result in bending forces being applied to the bolt. For thebolt to carry these bending moments, the bolt diameter needs to beincreased to sustain them. The increased bolt size therefore results ineven greater eccentricity, which compounds itself.

A fitting is machined, forged, or extruded from a single material.Certain parts of the fitting are loaded in tension, while others areloaded in compression or shear. The materials used for current fittingsare selected to handle these different loads in different parts of thefitting. This can result in inefficiencies, such as extra weight of thefitting and costs. Accordingly, fittings are needed that take intoconsideration the different loads carried by different portions of thefittings to be able to more efficiently carry the tension andcompression loads and at the same time provide reduced weight and cost.

SUMMARY

In accordance with an embodiment, a mechanical fitting for connectingstructures may include a first plate, end plate or base structure and asecond plate or plate member. The mechanical fitting may also include asupport structure for supporting the plate member at a predeterminedspacing from the end plate or base structure.

In accordance with another embodiment, a mechanical fitting forconnecting structures may include a first plate, end plate or basestructure and a second plate or plate member. The mechanical fitting mayalso include at least one side wall extending from the end plate or basestructure for attachment to a structure. The mechanical fitting mayadditionally include a first sloping plate extending between the platemember and a vertex formed by the at least one side wall and the basestructure. The first sloping plate may extend from the base structure ata first predetermined angle relative to a plane of the base structure.The mechanical fitting may further include a second sloping plateextending between the plate member and the base structure. The secondsloping plate may extend from the base structure at a secondpredetermined angle relative to the plane of the end plate.

In accordance with another embodiment, a method for connectingstructures may include receiving one end of a fastener through anopening in a base structure of a mechanical fitting to fasten thefastener to a mating mechanical fitting. The method may also includeretaining an opposite end the fastener by a plate member of themechanical fitting. The opposite end of the fastener is adapted to beheld by the plate member. The method may additionally include extendinga first sloping plate between the plate member and the base structure.The first sloping plate may extend from the base structure at a firstpredetermined angle relative to a plane of the base structure. Themethod may further include extending a second sloping plate between theplate member and the base structure. The second sloping plate may extendfrom the base structure at a second predetermined angle relative to theplane of the base structure.

Other aspects and features of the present disclosure, as defined solelyby the claims, will become apparent to those ordinarily skilled in theart upon review of the following non-limited detailed description of thedisclosure in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description of embodiments refers to theaccompanying drawings, which illustrate specific embodiments of thedisclosure. Other embodiments having different structures and operationsdo not depart from the scope of the present disclosure.

FIG. 1 is a perspective view of an example of a prior art angle clipuseable in connecting structures.

FIG. 2A is a perspective view of an example of a prior art channeltension clip useable in connecting structures.

FIG. 2B is a top view of the prior art channel tension clip in FIG. 2Aillustrating forces or loads on the channel tension clip and internaltension and compression stresses within the clip.

FIG. 3 is a perspective view of an example of a prior art angle fittingfor use in connecting structures.

FIG. 4 is a perspective view of an example of a prior art channelfitting for use in connecting structures.

FIG. 5A is a perspective view of an example of a mechanical fitting forconnecting structures including an end pad support structure inaccordance with an embodiment of the present disclosure.

FIG. 5B is a top view of the truss channel tension clip including thetruss end pad fitting of FIG. 5A illustrating forces or loads on thetension clip and truss end pad fitting and internal tension andcompression stresses within the fitting.

FIG. 6 is a top view of a truss end pad mechanical fitting and a matingtruss end pad mechanical fitting connecting structures in accordancewith an embodiment of the present disclosure.

FIG. 7 is a top view of an example of a truss channel tension clipincluding a truss end pad fitting in accordance with another embodimentof the present disclosure.

FIG. 8 is a top view of an example of a truss channel tension clipincluding a truss end pad fitting in accordance with a furtherembodiment of the present disclosure.

FIG. 9 is a top view of an example of a truss channel tension clipincluding a truss end pad fitting in accordance with yet a furtherembodiment of the present disclosure.

FIG. 10 is a top view of an example of a truss channel fitting includinga truss end pad fitting in accordance with an embodiment of the presentdisclosure.

FIG. 11 is a perspective view of an example of a truss channel fittingwithout a toe area and including a truss end pad fitting in accordancewith an embodiment of the present disclosure.

FIG. 12 is a perspective view of an example of a truss channel fittingincluding a truss end pad fitting in accordance with another embodimentof the present disclosure.

FIG. 13A is a perspective view of an example of a truss angle fittingincluding a truss end pad fitting in accordance with an embodiment ofthe present disclosure.

FIG. 13B is an end view of the exemplary truss angle fitting of FIG. 13Ataken along lines 13B-13B, illustrating internal tension and compressionstresses within the fitting.

FIG. 14 is top view of a pair of prior art angle tension clips fastenedtogether for connecting two structures.

FIG. 15A is a top view of a pair of truss angle tension clips includinga truss end pad support structure for joining two structures inaccordance with an embodiment of the present disclosure.

FIG. 15B is a top view of the pair of truss angle tension clips of FIG.15A illustrating forces or loads on the tension clip and truss end padfitting, and internal tension and compression stresses within thefitting.

FIG. 16 is a top view of a pair of prior art angle tension fittingsfastened together for connecting two structures.

FIG. 17A is a top view of a pair of truss angle tension fittingsincluding a truss end pad support structure for joining two structuresin accordance with an embodiment of the present disclosure.

FIG. 17B is a top view of the pair of truss angle tension fitting ofFIG. 17A illustrating forces or loads on the truss angle tension fittingand internal tension and compression stresses within the fitting.

FIGS. 18A-18E are each a top view of different fittings including arectangular polygon truss end pad fitting in accordance with anembodiment of the present disclosure.

FIGS. 18F, 18G, 18H, 18I and 18J are each a trimetric view of differentfittings in which the end plate is removed or altered in accordance withan embodiment of the present disclosure.

FIGS. 19A-19E are each a top view of different fittings including anirregularly shaped truss end pad fitting in accordance with anembodiment of the present disclosure.

FIG. 20A is a perspective view of a portion of another truss channelfitting in accordance with an embodiment of the present disclosure.

FIG. 20B is a plan view of the exemplary truss channel fitting of FIG.20A, showing two mating fittings.

FIG. 20C is a cross-section view of the exemplary truss channel fittingof FIG. 20B taken along lines 20C-20C.

FIG. 20D is a cross-sectional view of the exemplary truss channelfitting of FIG. 20B taken along lines 20D-20D.

FIG. 20E is an end view of the exemplary truss channel fitting of FIG.20B taken along lines 20E-20E.

FIG. 21 is an example of a sloping plate for use in a truss end padfitting in accordance with an embodiment of the present disclosure.

FIGS. 22A-22J are each an example of a different cross-section of thesloping plate taken along lines 22A-22J of FIG. 21, each in accordancewith a different embodiment of the present disclosure.

FIG. 23 is a flow chart of an example of a method for connecting a firststructure to at least one other structure in accordance with anembodiment of the present disclosure.

DESCRIPTION

The following detailed description of embodiments refers to theaccompanying drawings, which illustrate specific embodiments of thedisclosure. Other embodiments having different structures and operationsdo not depart from the scope of the present disclosure. Like referencenumerals may refer to the same element or component in the differentdrawings.

FIG. 5A is a perspective view of an example of a mechanical fitting 500useable for connecting structures including an end pad support structure502 in accordance with an embodiment of the present disclosure. Theexemplary mechanical fitting 500 in FIG. 5A is a truss channel tensionclip type mechanical fitting. The support structure or end pad supportstructure 502 will be initially described with reference to the trusschannel tension clip type mechanical fitting; although, the end padsupport structure 502 or variations thereof may be used in associationwith other types of fittings as described herein or as will beunderstood by those skilled in the art. The mechanical fitting 500 mayinclude a first plate, end plate or base structure 504 and second plateor plate member 506. The end pad support structure 502 or end padsupport structure supports the second plate or plate member 506 at apredetermined spacing from the base structure 504. The base structure504 and the plate member 506 may be substantially parallel to oneanother but do not necessarily have to be. For example, the plate member506 may be oriented at a predetermined angle relative to a plane of thebase structure 504.

The end pad support structure 502 may include a truss support structure508 or similar structure. The truss support structure 508 may include afirst sloping plate 510 extending between the plate member 506 and thebase structure 504. The first sloping plate 510 extends from the basestructure 504 at a first predetermined angle θ relative to a plane ofthe base structure 504 illustrated by line 512 in FIG. 5B.

The truss support structure 508 also includes a second sloping plate 514extending between the plate member 506 and the base structure 504. Thesecond sloping plate 514 may extend from the base structure 504 at asecond predetermined angle Θ relative to the plane 512 of the basestructure 504. The first predetermined angle θ and the secondpredetermined angle Θ may be equal to one another or in otherembodiments may be different angles similar to that illustrated in FIG.9.

The mechanical fitting 500 may also include a fastener 516. The fastener516 may be a bolt or other type of fastener similar to that describedherein. A hole or opening 518 may be formed in the base structure 504for receiving the fastener 516. Another hole or opening 520 may beformed in the plate member 506 for receiving the fastener 516. Thefastener 516 may be adapted to attach the mechanical fitting 500 to amating mechanical fitting similar to that illustrated in FIGS. 6, 15Aand 17A.

The mechanical fitting 500 may include at least one side wall extendingfrom the base structure 504. In this configuration the mechanicalfitting 500 would represent an angle clip truss fitting similar to eachof the mating angle clip truss fittings illustrated in FIGS. 15A and15B. The mechanical fitting 500 or truss channel tension clip asillustrated in FIGS. 5A and 5B includes a first side wall 522 and asecond side wall 524. The side walls 522 and 524 may extend fromopposite ends of the base structure 504 on either side of the end padsupport structure 502 or truss support structure 508. The first slopingplate 510 may extend between the plate member 506 and a vertex 526formed by the base structure 504 and the first side wall 522. The secondsloping plate 514 may extend between the plate member 506 and a vertex528 formed by the base structure 504 and the second side wall 524.Because the truss support structure 508 resolves the system of forces byinternal tension and compression loads and minimizes bending moments inthe members 504, 510, and 514, there will be less moments transferredinto the side walls 522 and 524. For this reason, the side walls 522 and524 may be thinner compared to traditional mechanical fittings, such asthose illustrated in FIGS. 1-4.

In accordance with different embodiments, the truss support structure508 may replace the end pad in traditional tension fittings, such asthose illustrated in FIGS. 1-4 and any variations thereof or types ofmechanical fittings in addition to those illustrated and describedherein.

FIG. 5B is a top view of the mechanical fitting 500 including the trusssupport structure 508 of FIG. 5A illustrating forces or loads on themechanical fitting 500 and truss support structure 508 and internaltension and compression stresses within the mechanical fitting 500. Thesloping plates 510 and 514 transmit the fastener or bolt tension load tothe side walls 522 and 524 via load components acting parallel to thefastener 516 or tension bolt. Because of the slope, these sloping plates510 and 514 also transmit a horizontal component of load into thevertices 526 and 528. The load components in the side walls 522 and 524are tension load components as illustrated by arrows 530 and 532 in FIG.5B. The sloping plates 510 and 514 carry only compression loads asillustrated by arrows 534 and 536 in FIG. 5B. The end plate or basestructure 504 carries the horizontal load components actingsubstantially perpendicular to the fastener 516 transmitted by thesloping plates 510 and 514. The base structure 504 carries only tensionloads as illustrated by arrows 538 and 540 in FIG. 5B.

Applying tension to the fastener 102 or bolt in the prior art end platemechanical fittings in FIGS. 1-4, respectively, places the end plate 102of the fitting in compression when the end plate 102 is abutted againstthe end plate 102 of a mating fitting similar to that illustrated inFIG. 14. In the mechanical fitting 500, the bolt or fastener tension isacted on by the sloping members 510 and 514 in axial compression asillustrated in FIG. 5B and previously described. The sloping plates 510and 514 may also be referred to as compression members or pyramid sides.The proportions and dimensions of the mechanical fitting 500 in thevicinity of the fastener 516 are formed such that the bolt tension willnot apply significant bending moments into the sloping plates 510 and514 or compression members of the truss structure 508.

The forces in the sloping plates 510 and 514 or compressive members arereacted by the base structure 504 and the side wall at each side wall522 and 524. A vertical component of the force in the sloping plates 510and 514 is carried solely by the side walls 522 and 524. The horizontalcomponent of the force in the sloping plates 510 and 514 is carried bythe base structure 504.

In the exemplary embodiment illustrated in FIGS. 5A and 5B, the fastener516 is mid-way between the two side walls 522 and 524. Each side wall522 and 524 will carry substantially one-half of the tension force inthe fastener 516. The magnitude of the load carried by the basestructure 504 will vary depending on the angles θ and Θ a between eachsloping plate 510 and 514 and the base structure 504. A large angle θ orΘ will result in less force being carried by the base structure 504. Asmaller angle θ or Θ a will result in more force being carried by thebase structure 504.

The geometry of the intersection of the sloping plates 510 and 514, basestructure 504, and side walls 522 and 524 may be formed so that themid-surfaces of each member meet in a common intersection point. Asillustrated in FIG. 5B, broken lines are shown extending down themid-surfaces of sloping plate 514, base structure 504 and side wall 524which meet at a common point 542. This arrangement minimizes bendingmoments in the compressive sloping plates 510 and 514, base structure504, and side walls 522 and 524 resulting from eccentricities that wouldoccur if the locations of the forces were not lined up in this manner.

FIG. 6 is a top view of an example of a truss end pad mechanical fitting600 and a mating truss end pad mechanical fitting 602 connectingstructures 606 and 608 in accordance with an embodiment of the presentdisclosure. The exemplary truss end pad mechanical fittings 600 and 602illustrated in FIG. 6 are each similar to the truss channel tension cliptype mechanical fitting 500 including a truss support structure 508similar to that described with reference to FIGS. 5A and 5B. The trussend pad mechanical fittings 600 and 602 may butt against one another asillustrated in FIG. 6. The fastener 516 or tension bolt connects the twofittings 600 and 602 together. The side walls 522 and 524 may alsosupport structures. In the example illustrated in FIG. 6 side wall 522of truss end pad fitting 602 supports structure 606 and side wall 522 oftruss end pad fitting 602 supports structure 608. The structures 606 and608 may be attached to the side wall 522 by fasteners or by anothersuitable attachment mechanism. The structures 606 and 608 may bestructures, assemblies or subassemblies of an aircraft or structure,such as a bridge, building or other civil structure. There may be a gapG between structures 606 and 608.

The truss end pad mechanical fitting 600 may be made from a single pieceof material similar to the exemplary mechanical fitting 500 describedwith reference shown in FIGS. 5A and 5B or the fitting may be formedfrom different components. FIG. 7 is a top view of an example of a trussend pad mechanical fitting 700 including a truss support structure 708which is a separate component in accordance with another embodiment ofthe present disclosure. The truss support structure 708 may include asecond plate or plate member 706 and first and second sloping plates 710and 714 that may be integrally formed separate from the end plate orbase structure 704 and side walls 722 and 724. An end of each of thesloping plates 710 and 714 may abut or contact a vertex 726 and 728formed by base structure 704 and each of the side walls 722 and 724.

The truss support structure 708 may be made from a different materialfrom the base structure 704 and side walls 722 and 724. Materials may beselected for the truss support structure 708 such that the first andsecond sloping plates 710 and 714 are formed from a material havingadvantageous mechanical properties in compression or mechanicalproperties that are more resistant to compression forces or loadsbetween the base structure 704 and the plate member 706 compared to amaterial that may be selected to form the base structure 704 and sidewalls 722 and 724. Similarly, the material for the base structure 704and side walls 722 and 724 may be selected to provide advantageousmechanical properties under tension loads or forces or more resistant totension loads or forces.

Additionally, materials having different properties, such as differentelectrical, conductive, thermal, insulating or other advantageousproperties, may be selected to form the truss support structure 708 andbase structure 704 and side walls 722 and 724 depending upon theapplication or use of the fitting. The truss support structure 708 isalso applicable to other types of mechanical fittings. The truss supportstructure 708 may also be referred to as a compression member. The crosssectional area of the sloping members 710 and 714 may be increased atthe ends of the members where they contact the vertices 730 and 732.This additional area may reduce the bearing stresses in the members 710,714, and in the material near the vertices 730 and 732. In addition, theincreased radii of the ends of the sloping members 710 and 714 can mateto fillet radii 734 and 736, further reducing stress concentrations inthe base structure 704. In addition, surface preparations including, butnot limited to shot peening, lubricants, and coatings may protect thecontact surfaces between the base structure 704, fillet radii 734 and736 and truss support structure 708. Furthermore, the truss supportstructure 708 may be made of an electrically insulative material, whichmay be advantageous in certain applications.

FIG. 8 is a top view of an example of a truss end pad mechanical fitting800 including a truss support structure 808 in accordance with a furtherembodiment of the present disclosure. The truss end pad mechanicalfitting 800 may be similar to the mechanical fittings 500 and 700 exceptthe fastener 516 or bolt may be replaced by another type of tensionmember, such as a band 816 or other type tension member. Anotherdifference may be the sloping plates 810 and 814 or compression membersare not integrally formed with the second plate or plate member 806. Oneadvantage of the tension member or band 816 relative to a threaded boltis that the band 816 eliminates the threads and thus the band 816 may bemore efficient. To add tension to the tension member or band 816, aforce may be applied to the band 816 as illustrated by arrow 834 toinduce tension into the band 816 and compression into the compressionmembers or sloping plates 810 and 814.

The band 816 may be integrally formed with the plate member 806 asillustrated in FIG. 8 or the plate member 806 may be attached to theband 816 by some mechanism. The first sloping plate 810 may include afirst end 826 abutting a vertex formed by the band 816 and the platemember 806. An opposite end 828 of the first sloping plate 810 abuts avertex formed by a first side wall 822 and the end plate or basestructure 804. The first sloping plate 810 may extend from the basestructure 804 at a first predetermined angle θ relative to a plane ofthe base structure 804.

The second sloping plate 814 may include a first end 830 abutting avertex formed by the band 816 and the plate member 806. An opposite end832 of the second sloping plate 814 may abut a vertex formed by the basestructure 804 and a second side wall 824 of the truss end pad mechanicalfitting 800. The second sloping plate 814 may extend from the basestructure 804 at a second predetermined angle Θ relative to the plane ofthe base structure 804. The band 816 and first and second sloping plates810 and 814 are also applicable to other types of mechanical fittings.

FIG. 9 is a top view of an example of a truss end pad mechanical fitting900 including a truss support structure 908 in accordance with yet afurther embodiment of the present disclosure. The truss end padmechanical fitting 900 may be similar to the mechanical fitting 500 inFIG. 5A except the fastener 916 may be closer to one of the side wallsand the truss support structure 908 may be off-center similar to thatillustrated in FIG. 9. The truss end pad mechanical fitting 900 mayinclude a side wall 924 that may be thicker in relation to the otherside wall 922 in proportion to the distances of the fastener 916 fromthe respective side walls 922 and 924. Additionally, the angles of thesloping members 910 and 914 will be different relative to a plane of theend plate or base structure 904 and a thickness of the sloping members910 and 914 may vary to accommodate the different compressive loads. Theangles and thicknesses of the sloping members 910 and 914 may beadjusted to maintain a minimum weight of the mechanical fitting 900 andto minimize any moments resulting from eccentricities.

The support structures or truss support structures 508-908 describedwith reference to FIGS. 5-9 are also applicable to other types offittings. FIG. 10 is a top view of an example of a truss channel fitting1000 including a truss support structure 1008 in accordance with anembodiment of the present disclosure. The truss channel mechanicalfitting 1000 includes an adjoining sidewall or backplane 1026 betweenside walls 1022 and 1024. Otherwise, the truss channel fitting 1000 issimilar to the mechanical fitting 500 described with reference to FIGS.5A and 5B. Because the width of the sloping plates 1010 and 1014 orcompressive members varies from a smaller width “W1” near the bolt 1016to a larger width “W2” near the side walls 1022 and 1024, thethicknesses of the sloping plates 1010 and 1014 may also be varied froma thicker dimension near the bolt 1016 to a thinner dimension orthickness near each side wall 1022 and 1024. The width and thickness ofthe sloping plates 1010 and 1014 or compressive members may be variedsuch that the cross sectional area of the sloping plates 1010 and 1014may be substantially constant.

The exemplary truss end pad fittings described herein may provide astiffness or rigidity for connection of structures that approaches thatof the parent material of the structures. This may be because theexemplary truss end pad fittings described herein provide a direct loadpath from the tension member (e.g. fastener or bolt) through the slopingplates or compression members into the area of the end plate or basestructure that abuts an adjacent mirror or mating fitting to which anopposite end of the tension member attaches, similar to that illustratedin FIG. 6. Thus, there is no longer a need for a “toe” area that istypically required in prior art fittings, such as toe area 408 in FIG.4. The opening 1028 illustrates removal of the toe area.

FIG. 11 is a perspective view of an example of a truss channel fitting1100 without a toe area and including a truss end pad structure 1108 inaccordance with an embodiment of the present disclosure. The opening1102 illustrates the removed toe area. The force from the fastener ortension member 1116 is carried directly through the sloping plates 1110and 1114 or compression members into the end plate or base member orstructure 1104 and side walls 1122 and 1124. Longitudinal components ofthe forces are carried by the sidewalls 1122 and 1124 to the backplane1126 through shear. The truss channel fitting 1100 may be effectivelyclamped with an adjacent mirrored fitting on another side at theintersection of the sloping plates 1110 and 1114 and the side walls 1122and 1124 and is not clamped at the location of the bolt or fastener asin prior art end pad fittings without a truss structure as describedherein.

As previously discussed, a limitation of prior art fittings is the sizeof the fillet radius between the backplane and the end plate or pad topreclude premature cracking at that fillet radius. The exemplary trusschannel fitting 1100 in FIG. 11 avoids this deficiency by eliminating ajoint between the base member or structure 1104 and the backplane 1126by removing the toe area by forming the opening 1102. Because the loadpath no longer travels directly between the tension member 1116 and thebackplane 1126, the intersection of those two elements has been removed.Furthermore, since the presence of material in that portion of thefitting would be low stress if it were present, and it is not necessaryfor stability of any of the other parts of the fitting, the material inthe backplane near the front of the fitting can be removed to form theopening 1102, thus having the “scalloped” feature illustrated in theembodiments of FIGS. 10 and 11.

This concept can also be used to handle a larger eccentricity, forexample, the exemplary truss channel fitting 1200 with a largeeccentricity of the bolt 1216 in FIG. 12. FIG. 12 is a perspective viewof an example of a truss channel fitting 1200 including an eccentrictruss end pad structure 1208 in accordance with another embodiment ofthe present disclosure. In this embodiment, side members 1222 and 1224that function like trusses replace the solid sidewalls 1122 and 1124 inFIG. 11. In this fitting, just as in the truss channel fitting 1100illustrated in FIG. 11, the bolt 1216 tension load is carried by thecompressive members 1210 and 1214 to the side members 1222 and 1224, butinstead of transferring the load to the backplane 1226 by shear, theload is carried in axial tension through the side members 1222 and 1224.This axial tension is then sheared into the backplane 1226 near an end1228 of the truss channel fitting 1200.

With the higher eccentricity of the truss support structure 1208, ahorizontal member may be needed to prevent the truss channel fitting1200 from opening up at the backplane 1226 near the scallop 1202. If thehole 1218 in the base member or structure 1204 is a close-fit hole, thepossibility of transmitting lateral loads into the truss channel fitting1200 is present. A loose fit hole 1218 is illustrated in FIG. 12 toavoid the possibility of transmitting the lateral loads into the trusschannel fitting 1200. In this case, diagonal members 1230 and 1232 canbe added as illustrated in FIG. 12 to efficiently transfer this lateralload.

FIG. 13A is a perspective view of an example of a truss angle fitting1300 including a truss end pad structure 1308 in accordance with anembodiment of the present disclosure. FIG. 13B is an end view of theexemplary truss angle fitting 1300 of FIG. 13A taken along lines13B-13B. FIG. 13B also shows the internal tension and compressionstresses in the end plate 1304 and the sloping plates 1310 and 1314.Similar to the other mechanical fittings described herein, the tensionin the bolt 1316 or other fastener is carried by the two sloping plates1310 and 1314 or compression members into a base structure 1304 and sidewalls 1322 and 1324. In the truss angle fitting 1300 depicted in FIGS.13A and 13B, the forces transmitted into the side walls 1322 and 1324 bythe compression members 1310 and 1314 or sloping plates are thus carriedto an end portion 1320 of the truss angle fitting 1300 by upper outerchords 1326 and 1328 of the side walls 1322 and 1324, respectively thatmeet or come together proximate the end portion 1320 of the truss anglefitting 1300.

FIG. 14 is top view of a pair of prior art angle clips 100 fastenedtogether for connecting two structures 1400 and 1402. The angle clips100 are similar to the angle clip 100 described with reference toFIG. 1. FIG. 15A is a top view of a pair of truss angle tension clips1500 each including a truss end pad support structure 1502 for joiningtwo structures 1504 and 1506 in accordance with an embodiment of thepresent disclosure. FIG. 15B is a top view of the pair of truss angletension clips 1500 of FIG. 15A illustrating forces or loads on the trussangle tension clips 1500 and truss end pad support structure 1502, andthe tension and compression stresses within the members of the fitting.Each of the truss angle tension clips 1500 may include a base member orbase structure 1508 and a plate member 1510. A first sloping plate 1512and a second sloping plate 1514 or compression members may extendbetween the plate member 1510 and the base structure 1508. The trussangle tension clips 1500 may be clamped together by a tension member1516 or bolt. Each of the truss angle tension clips 1500 include a sidewall 1518 extending from the base structure 1508. Each side wall 1518may extend substantially perpendicular to the base structure 1508,although depending upon the application, the side wall 1518 may extendfrom the end plate 1508 at some other angle. The truss end pad supportstructure 1502 eliminates bending from the tension member 1516.Accordingly, the tension member 1516 can be made smaller than thetension member associated with the prior angle clip 100 in FIG. 14.Additionally, the thicknesses of the side walls 1518 can be reducedcompared to the side walls 108 as illustrated by comparing FIGS. 15A and15B to FIG. 4 because bending stresses are substantially minimized bythe truss end pad support structure 1502 relative to the prior art angleclip 100 in FIG. 14.

As illustrated in FIGS. 15A and 15B, the sloping plate 1512 orcompression member on one side of the truss end pad structure 1502 doesnot have a side wall or vertical leg adjacent to it. This isinconsequential, because the purpose of the truss fitting is to firmlyclamp the two side walls 1518 together at the mating surfaces betweenthe two fittings. The sloping plates 1512 and 1514 or compressionmembers are present only because symmetry is required, so that theforces at the head of the tension member 1516 and along the matingsurface of the base members or structures 1508 are balanced. There isforce balance from the sloping plates 1512 and 1514 except for a nethorizontal force. The net horizontal force is balanced by the pair ofbase structures 1508 in tension.

The sloping plates 1512 and 1514 or compression member arrangementillustrated in FIGS. 15A and 15B may also be applied to angle fittings,channel fittings and other mechanical fittings. FIG. 16 is a top view ofa pair of prior art angle tension fittings 1600 fastened together forconnecting two structures 1602 and 1604. FIG. 17A is a top view of apair of truss angle tension fittings 1700 each including a truss end padsupport structure 1702 for joining two structures 1704 and 1706 inaccordance with an embodiment of the present disclosure. FIG. 17B is atop view of the pair of truss angle tension fitting 1700 of FIG. 17Aillustrating forces or loads on the tension clip and truss end padstructure 1702, and the internal tension and compression stresses. Inthe embodiment in FIGS. 17A and 17B, the truss end pad supportstructures 1702 are separate components from the truss angle tensionfitting 1700 and are separately formed. The truss end pad supportstructure 1702 may be similar to the truss support structure 708described with reference to FIG. 7, or it may be arranged in an integralmanner as described with reference to FIG. 6. In other embodiments, thetruss end pad support structure 1702 may be arranged as separate piecesas described with reference to FIG. 8. While the fittings 1500 and 1700in FIGS. 15 and 16 are shown to mirror one another or to besubstantially identical, they do not need to be and have differentconfigurations or be different types of fittings.

One aspect of the truss angle tension fitting 1700 is that it canprovide a smooth transfer of load from one fitting to its mating fittingalong all of the boundaries which have backup structure. A significantbenefit of the truss end pad arrangement is that it allows the matingsurfaces to be clamped very close to the location of the mating surface,in contrast to the prior art fittings, which are clamped at a remotelocation (at the bolt or tension member), as discussed in paragraph[0003] for the prior art fittings. The prior art fittings show atendency to “open up” at the end pad bends, thus decreasing the jointstiffness. The fittings described in the invention will maintain theirjoint stiffness at higher loads, until the tension member stretches somuch that the fittings separate. Thus, in the case of angle clips, oneedge is firmly clamped. In the case of channel tension clips, twoopposite sides are clamped. In the case of angle clips, two adjacentsides are clamped. In the case of channel fittings, three sides areclamped. For angle tension clips, an additional edge is also clamped.This additional edge does not transfer axial loads from one fitting tothe other fitting, but it provides for a nearly symmetrical system offorces for the bolt, compression members, and the other leg or side wallof the angle tension fitting.

For angle fittings and channel fittings, all four edges are clamped,even though not all of those edges transfer load from one fitting to themating fitting. However, just as in the case of the angle tension clip,clamping the other edges provides for load balance at the bolt,compression members or sloping plates, and side walls.

The different embodiments of truss end pad fittings have beenillustrated and described using a rectangular polygon, with a subset ofthe edges of the rectangular polygon being used to transfer the loadfrom one fitting to the mating fitting. FIGS. 18A-18E are each a topview of different fittings 1800-1808 including a rectangular polygontruss end pad fitting in accordance with an embodiment of the presentdisclosure. The fitting in FIG. 18A is an angle tension clip 1800 with aside wall extending from only one side 1810 (illustrated by thecross-hatching) of the angle tension clip 1800. The fitting in FIG. 18Bis a channel tension clip including side walls 1812 and 1814(illustrated by cross-hatching) extending from two opposite sides of thetruss end pad fitting 1802. The fitting in FIG. 18C is an angle fitting1804 including side walls 1816 and 1818 extending from two adjacentsides of the angle fitting 1804. The fitting in FIG. 18D is a channelfitting 1806 including side walls 1820, 1822 and 1824 extending fromthree sides of the channel fitting 1806. The fitting in FIG. 18E is afull surround fitting 1808 including side walls 1826-1832 extending fromall four sides of the full surround fitting 1808. The side walls areillustrated by cross-hatching in FIGS. 18A-18E.

Referring now to FIG. 18F, a channel tension fitting 1830 isillustrated. This configuration differs from those discussed thus far inthat it does not have an end plate included. The function of the endplate (to prevent the base of the pyramid shape 1832 from spreadingapart) is performed by the lower portions of the sloping pyramid shape1832 being stretched in tension in a direction parallel with the base ofthe pyramid 1832 and substantially perpendicular to the longitudinalaxis of the fastener 1833. A base structure or base member 1834 of eachfitting extending from the side walls 1836 and 1838 may only extendpartially between the side walls 1836 and 1838. FIG. 8G shows only thepyramid 1832 with the tension forces and compression forces in thepyramid 1832 indicated. The compression forces in the pyramid sides areoriented similar to the compression forces in the sloping platesillustrated in FIGS. 5B, 15B, and 17B. The lower portion of the pyramidsides near the base experience tension in a circumferential directionaround the base of the pyramid 1832.

FIG. 18H is an example of another embodiment of a pyramid shape 1840. InFIG. 18H, material has been added to the base plane of the pyramid 1840,making this configuration or embodiment stiffer and more efficientcompared to the configuration illustrated in FIG. 18G.

FIG. 18I is an example of another embodiment of a pyramid 1842. In FIG.18I, the sloping plates of the pyramid 1832 have been replaced byelongate members substantially along the edges of the pyramid 1842.These elongate members carry compression forces. The perimeter of thebase of the pyramid 1842 is also comprised of elongate members, whichcarry tension forces. Thus, the perimeter elongate members serve thesame restraining function as the end plate of the fittings illustratedin FIGS. 5B, 15B, and 17 b which include end plates.

The configuration or embodiment of the pyramid 1844 shown in FIG. 18 jis similar to that illustrated in FIG. 18I, except that the perimeterelongate members have been replaced by diagonal elongate members. Thediagonal elongate members carry tension forces, and also serve therestraining function as the perimeter elongate members of theconfiguration shown in FIG. 18I. It will be appreciated by one skilledin the art that the material in the pyramids and base can be arranged inmany ways, of which only a few are illustrated herein.

With reference to FIG. 18H it is noted that the material in the baseplane 1846 of the fitting is in the plane of the base. In reference toFIG. 18J, it is noted that the elongate members are arranged such thatthey are some distance away from the plane of the base which mates toanother structure or adjoining fitting, and are thus closer to the bolthead. This distance will cause small moments to be generated in thesloping elongate members. However, if it is advantageous to arrange theperimeter elongate members in this manner due to greater ease ofmanufacturing, these relatively small moments can be easily tolerated.This general principle applies to all fittings in this disclosure.Although the greatest benefit due to weight savings can be realized byarranging the sloping plates and/or elongate members such that theycarry only axial tension or compression forces, small moments created bysmall departures from the ideal geometry can be tolerated if other suchas easier manufacturing or ease of assembly provide a significantbenefit.

Truss end pad fittings may also be formed in different shapes or mayinclude end plates of different shapes, such as for example irregularpolygons of three or more sides. A subset of these edges may transferloads from one fitting to the mating fitting. There is no limitation asto the arrangement of sides which transfer or not transfer load. Forbest efficiency, compression members or sloping plates are located atthose points or edges which have mating structure. FIGS. 19A-19E areeach a top view of a different fitting 1900-1908 including anirregularly shaped truss end pad fitting in accordance with anembodiment of the present disclosure. Side walls extending from theirregular fittings 1900-1908 are illustrated by cross-hatching the sidewall extending out of the page. FIGS. 19D and 19E illustrate that theside walls of the fitting need not be straight. Although straight sidewalls, sloping plates, and end plates are typically the most efficient,non-straight side walls, sloping plates, or end plates can be used.

FIG. 20A is a perspective view of a portion of an example of a truss endpad fitting 2000 in accordance with an embodiment of the presentdisclosure. FIG. 20B is a plan view of the exemplary truss end padfitting 2000 of FIG. 20A. FIG. 20C is a cross-section view of theexemplary truss end pad fitting 2000 of FIG. 20B taken along lines20C-20C. FIG. 20D is a cross-sectional view of the exemplary truss endpad fitting 2000 of FIG. 20B taken along lines 20D-20D. FIG. 20E is anend view of the exemplary truss end pad fitting of FIG. 20B taken alonglines 20E-20E.

Each truss end pad fitting 2000 includes a support fitting 2002. Thesupport fitting 2002 may include an integrally formed end plate, basestructure or membrane 2004 and side walls 2006 and 2008. The membrane2004 and side walls 2006 and 2008 may form a cavity 2209 in the supportfitting 2002. The truss end pad fitting 2000 may also include a tensionmember or band 2010. The band 2010 carries the tension loads andreplaces the fastener or bolt in conventional truss end pad fittings. Asbest illustrated in FIG. 20C, the base structure or membrane 2004 ofsupport fitting 2002 includes an opening therein 2011 through which theband 2010 may extend between the mating support fittings 2002 a and 2002b as best illustrated in FIG. 20B. The base structure or membrane 2004 aof one support fitting 2002 a may be different than the base structureor membrane 2004 b of the mating support fitting 2002 b as illustratedin FIG. 20B. The base structure or membrane 2004 a may bow into thecavity 2009 of the support fitting 2002 a. Or, the base structure ormembrane 2004 a may have a flange 2004 b that extends into the cavity2009 of the support fitting 2002 a. In other embodiments, the end platesmay be the same.

The truss end pad end pad fitting 2000 may also include a pair ofcompression members, sloping plates or elbows 2012 and 2014 to carrycompressive loads. The elbows 2012 and 2014 may be the same or similarto the sloping plates previously described.

A noodle 2016 or other retention mechanism prevents the band 2010 fromsliding past the elbows 2012 and 2014. The noodle 2016 may be any shapethat permits an end of each of the elbows 2012 and 2014 to be retainedas illustrated in FIGS. 20A and 20B. The band 2010 is a bifurcated bandincluding a first band segment 2010 a and a second band segment 2010 b.The band 2010 extends around the noodle 2016 and may define a secondplate or performs the function of the second plate in the previousembodiments. The noodle 2016 also replaces a bolt head or fastener headwhile also retaining the elbows 2012 and 2014, compression members orsloping plates. Accordingly, an end of the first elbow 2012 or slopingplate may abut a vertex or stop formed by the band 2010 extending aroundthe noodle 2016 or second plate. An opposite end of the first elbow 2012may abut a vertex formed by the membrane 2004 and side wall 2008 of thesupport fitting 2002. Similarly, the second elbow 2014 or sloping platemay abut a vertex or stop formed by the band 2010 extending around thenoodle 2016 and an opposite end of the first elbow 2012 may abut avertex formed by the membrane 2004 and the other side wall 2006 of thesupport fitting 2002. Each of the first elbows 2012 and second elbow2014 may extend from the membrane 2004 at a predetermined angle relativeto a plane of the membrane 2004.

The elbows 2012 and 2014 may be specially formed so that the ends of theelbows nest against the band segments 2010 a and 2010 b and the endplate or membrane 2004 of the support fitting 2002 such that bearingstresses may be reduced. The ends of the elbows 2012 and 2014 may betreated or coated with a material such that there is an advantageousinterface between the two materials of the elbows and the supportfitting 2002. For example, a coating may be selected to protect thecomponents from galvanic corrosion, to either increase or decrease thecoefficient of friction between the components, for example coated in alubricant, or a coating for some other desired purpose or performancecharacteristic. This feature may also be applied to the fittingsdescribed with reference to FIGS. 7 and 8. Strain gauge elements mayalso be installed or embedded in the elbows 2012 and 2014 to measureload in the fitting 2000.

The truss end pad fitting 2000 may also include a cam 2018 or similarfeature to spread the two segments of the band 2010 apart, thus inducingadditional tension in the band segments 2010 a and 2010 b. The band 2010replaces the bolt or other fastener in a conventional fitting. The cam2018 may include a knob 2019 for operating the cam 2018 to inducetension in the band 2010 as best illustrated in FIG. 20C. The band 2010may be made from a metallic material or any other material that has ahigh tensile strength. The band 2010 need not be extremely stiff but mayneed to be stiff enough so that the cam 2018 is effective in tighteningthe band segments 2010 a and 2010 b. The cam 2018 may be substantiallyelliptically shaped such that the cam 2018 is oriented with a smallerdimension perpendicular to the axis of the band 2010 during assembly.After all components of the fitting 2000 are in place, the cam 2018 maybe rotated such that the long dimension of the cam 2018 is perpendicularto the axis of the band segments 2010 a and 2010 b, thus spreading thesegments apart to provide tension in the band 2010 and to retain theelbows 2012 and 2014 in place. The tension provided by rotating the cam2018 results in a tensile strain being applied to the band segments 2010a and 2010 b sufficient to apply the desired amount of preload in thefitting 2000.

If the band 2010 is made from a solid metallic material, the band 2010may yield upon the spreading action of the cam 2018. Thus the band 2010may be a throw-away or disposable component similar to a cotter pin ifthe fitting 2000 is taken apart for maintenance. Further, the band 2010may be formed by a plurality of wires which may be wrapped around thenoodle 2016 like a cable. The plurality of wires may be quite stiff andstrong in tension but quite flexible in bending. Accordingly, thespreading action by the cam 2018 will not result in large bendingstresses in the plurality of wires near the noodle 2016 and near the cam2018. The allowable stresses of small wires are typically greater thanthey are for solid materials. Thus, a small cross-sectional area may beemployed. The plurality of wires may also provide resistance to theconsequences of fatigue. If one wire should crack the defect will notspread to the adjacent wires as may be the case for a solid malleablemetal band.

The band 2010 may also be made from fibers, such as carbon fibers,Kevlar or similar fiber materials which have very high strengths andstiffness. Kevlar is a trademark of E.I. Dupont de Nemours and Companyin the United States, other countries or both. Using such fibermaterials may result in even smaller cross-sectional areas which in turnreduces eccentricities similar to those previously described. If anon-metallic (non-conducting) material is used for the band 2010, asingle metallic wire (or small set of metallic wires) could function asa strain gauge for measuring the load in the band 2010, and thus, theload in the fitting 2000.

The cam 2018 may include a detent or other mechanism to permit lockingthe cam 2018 in position with the band 2010 in tension to prevent thecam 2018 from rotating out of its preferred alignment due to vibrationor other environmental effects.

A cover or retention bar 2020 may be provided to prevent the noodle 2016and elbows 2012 and 2014 from moving vertically away from a lower wall2022 of the support fitting 2002 and out of the cavity 2009 of thefitting 2000.

Because the band 2010, elbows 2012 and 2014, and other components areseparate, they can each be made from different materials havingdifferent material characteristics or properties, such as electricalconductive or insulative properties, thermally conductive or insulativeproperties or other material properties depending on the design andapplication of the fitting 2000. The components may also includefeatures to provide a degree of vibration isolation if desired orneeded. If the fitting 2000 is a more lightly loaded fitting, certaincomponents of the fitting may be replaced with a compliant material thatprovides some degree of isolation from vibration. These features canalso apply to the other fittings described herein.

FIG. 21 is an example of a truss support structure 2100 for use inmechanical fittings similar to those described herein in accordance withan embodiment of the present disclosure. The truss support structure2100 may also be referred to as a compression member. The truss supportstructure 2100 or compression member may be substantially pyramid shapedas illustrated in FIG. 21. Similar to that previously described trusssupport structure 2100 may include two sloping plates 2102 and 2104 orpyramid sides joined by an upper or top plate 2106. The top plate 2106may be adapted for receiving a fastener (not shown in FIG. 21). The topplate 2106 may have an opening 2108 formed therein for receiving atension member or fastener, such as a bolt or other fastener similar tothose described herein. The tension member or fastener may include ahead or fitting to abut or contact a periphery or boundary of theopening 2108 so that the fastener is held or retained by the trusssupport structure 2100 for applying tension to the fastener andcompression in the sloping plates 2102 and 2104 of the truss supportstructure 2100 or compression member similar to that illustrated anddescribed herein when tension is applied to the fastener.

The truss support structure 2100 in FIG. 21, and as illustrated in othertruss end plate fitting embodiments described above, is shown asincluding substantially flat sloping plates 2102 and 2104. For moreheavily-loaded fittings, the thickness T of the truss support structure2100 may need to be large enough compared to a slant height H of thesloping plates 2102 and 2104 that structural instability caused bybuckling or deformation may not be a concern. However, for morelightly-loaded fittings, the thickness of the sloping plates 2102 and2104 may be small enough such that if the form of the sloping plates maybuckle. In this case, the cross-section of the sloping plates 2102 and2104 need not be approximately constant, but may vary in thickness, orhave stiffening elements or may be formed in different shapes. FIGS.22A-22J are each an example of a different cross-section of the slopingplates 2102 and 2104 taken along lines 22A-22J in FIG. 21. Depending onthe application and loading, the sloping plates 2102 and 2104 may eachhave a different one of the exemplary cross-sections shown in FIGS.22A-22 j.

FIG. 23 is a flow chart of an example of a method 2300 for connecting afirst structure to at least one other structure in accordance with anembodiment of the present disclosure. The first structure and the atleast one other structure may be a structure of an aircraft, civilstructure or other assembly or subassembly. In block 2302, an end of afastener may be received through an opening in an end plate of amechanical fitting to fasten the fastener to a mating mechanical fittingfor connecting the first structure to at least one other structure.

In block 2304, an opposite end of the fastener is retained by a secondplate or upper plate of the mechanical fitting. The opposite end of thefastener is adapted to be held or retained by the second or top plate.

In block 2306, a first sloping plate or pyramid side of a compressionmember may extend between the second or upper plate and the end plate.The first sloping plate or pyramid side of the compression member mayextend from the end plate at a first predetermined angle relative to aplane of the end plate. The first sloping plate or pyramid side may beintegrally formed with the second or upper plate or may be a separatecomponent of a truss support structure or compression member. The firstsloping plate or pyramid side may be formed from a different materialthan the end plate to provide desired performance characteristics orselected properties such as superior performance under compressionloads, lighter weight, etc.

In block 2308, a second plate or pyramid side of a compression membermay be extended between the second or upper plate and the end plate. Thesecond sloping plate or pyramid side may extend from the end plate at asecond predetermined angle relative to the plane of the end plate. Thesecond sloping plate or pyramid side may be integrally formed with thesecond plate or may be a separate component of the support structure orcompression member. The second plate or pyramid side may also be formedfrom a different material from the end plate to provide desiredperformance characteristics or selected properties such as superiorperformance under compression loads, lighter weight, etc.

In block 2310, a structure, such as an aircraft structure, civilstructure or other structure may be attached to a side wall extendingfrom the end plate of the mechanical fitting to form an assembly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art appreciate that anyarrangement which is calculated to achieve the same purpose may besubstituted for the specific embodiments shown and that the embodimentsherein have other applications in other environments. This applicationis intended to cover any adaptations or variations of the presentdisclosure. The following claims are in no way intended to limit thescope of the disclosure to the specific embodiments described herein.

1. A mechanical fitting for connecting structures, comprising: a basestructure; a plate member; and a support structure for supporting theplate member at a predetermined spacing from the base structure, whereinthe support structure comprises: a first sloping plate extending betweenthe plate member and the base structure, wherein the first sloping plateextends from the base structure at a first predetermined angle relativeto a plane of the base structure; a second sloping plate extendingbetween the plate member and the base structure, wherein the secondsloping plate extends from the base structure at a second predeterminedangle relative to the plane of the base structure, wherein the firstsloping plate and the second sloping plate each comprise a stiffeningelement.
 2. The mechanical fitting of claim 1, further comprising: afastener; and a hole formed in the plate member for receiving thefastener, wherein the fastener is adapted to attach the mechanicalfitting to another mechanical fitting.
 3. (canceled)
 4. (canceled) 5.The mechanical fitting of claim 1, further comprising at least one sidewall extending from the base structure, the side wall being configuredfor attaching a structure and wherein the first sloping plate extendsbetween the plate member and a vertex formed by the base structure andthe at least one side wall.
 6. The mechanical fitting of claim 5,further comprising at least one other side wall extending from the basestructure, wherein the second sloping plate extends between the platemember and a vertex formed by the base structure and the at least oneother side wall.
 7. The mechanical fitting of claim 1, wherein the firstpredetermined angle and the second predetermined angle are equal. 8.(canceled)
 9. The mechanical fitting of claim 1, wherein the base, theplate member, the first sloping plate and the second sloping plate areintegrally formed from a same material.
 10. The mechanical fitting ofclaim 1, wherein the first sloping plate and the second sloping plateare integrally formed with the plate member. 11-20. (canceled)
 21. Themechanical fitting of claim 1, wherein the first sloping plate and thesecond sloping plate each have a cross-section comprising at least onerib that forms the stiffening element.
 22. The mechanical fitting ofclaim 1, wherein the first sloping plate and the second sloping plateeach comprise a wavy cross-section that provides the stiffening element.23. The mechanical fitting of claim 1, wherein the first sloping plateand the second sloping plate each comprise a T-shaped cross-section thatprovides the stiffening element.
 24. The mechanical fitting of claim 1,further comprising: a third sloping plate extending between the platemember and the base structure between the first and second slopingplates; and a fourth sloping plate extending between the plate memberand the base structure between the first and second sloping platesopposite the third sloping plate, the first, second, third and fourthsloping plates forming a pyramid like structure.
 25. The mechanicalfitting of claim 1, further comprising: a first side wall extending fromthe base structure; a second side wall co-extending from the basestructure with the first side wall and joined to the first side wall,the second side wall forming a predetermined angle with the first sidewall.
 26. The mechanical fitting of claim 25, wherein the first sidewall comprises a chord sloping downwardly from the base structure to aposition proximate an opposite end of the first side wall from the basestructure.
 27. The mechanical fitting of claim 26, wherein the secondside wall comprises a second chord sloping downwardly from the basestructure to a position proximate an opposite end of the second sidewall from the base structure.
 28. The mechanical fitting of claim 25,wherein the predetermined angle is a right angle.
 29. The mechanicalfitting of claim 25, wherein each of the side walls slope downward fromthe base structure and are level proximate an end opposite the basestructure.
 30. A mechanical fitting for connecting structures,comprising: a base structure; a plate member; a first side wallextending from one side of the base structure; a second side wallextending from an opposite side of the base structure; a first slopingplate extending between the plate member and a first vertex formed bythe first side wall and the base structure, wherein the first slopingplate extends from the base structure at a first predetermined anglerelative to a plane of the base structure and the first sloping platecomprising an end with an increased radius cross sectional area at thatmatingly fits a fillet radius of the vertex formed by the first sidewall and the base structure; and a second sloping plate extendingbetween the plate member and a second vertex formed by the second sidewall and the base structure, wherein the second sloping plate extendsfrom the base structure at a second predetermined angle relative to theplane of the base structure and the second sloping plate comprising anend with an increased radius cross section area at that matingly fits afillet radius of the vertex formed by the first side wall and the basestructure.
 31. A mechanical fitting for connecting structures,comprising: an end plate; a first side wall extending from the endplate; a second side wall co-extending from the end plate with the firstside wall and joined to the second side wall, the second wall forming apredetermined angle with the first wall; a truss end pad structurecomprising: a plate member; a first sloping plate extending between theplate member and a first vertex formed by the end plate and the firstside wall; and a second sloping plate extending between the plate memberand a second vertex formed by the end plate and the second side wall,wherein the first sloping plate and the second sloping plate eachcomprise a stiffening element.
 32. The mechanical fitting of claim 31,wherein the first side wall comprises a chord sloping downwardly fromthe end plate to a position proximate an opposite end of the first sidewall from the end plate.
 33. The mechanical fitting of claim 32, whereinthe second side wall comprises a second chord sloping downwardly fromthe end plate to a position proximate an opposite end of the second sidewall from the end plate.